Refrigerants

ABSTRACT

A refrigerant comprising (1) dichlorotrifluoroethane and (2) at least one compound selected from the group consisting of chlorotetrafluoroethane, pentafluoroethane, tetrafluoroethane, 1-chloro-1,1-difluoroethane, 1,1,1-trifluoroethane and 1,1-difluoroethane.

This is a division of application Ser. No. 07/259,144 filed Oct. 18,1988 now U.S. Pat. No. 4,957,652.

This invention relates to a working fluid for a refrigerator, namely arefrigerant.

Refrigerants heretofore known include chlorofluoroalkanes,fluoroalkanes, azeotropic compositions thereof and like compositionswhich are generally called CFCs. In recent years, however, it has beensuggested that fully halogenated CFCs, i.e. fully halogen-substitutedalkanes, released into the atmosphere would deplete the stratosphericozone layer, thereby inflicting a serious adverse influence on theecosystem including humans on the earth. A worldwide agreement, "TheMontreal Protocol," signed in September 1987, calls for a restriction ofconsumption and production of the major ozone-depleting CFCs. Among theCFCs to be controlled for the restriction is trichlorofluoromethane(hereinafter referred to as "R-11"). With the spread of refrigeratorsand air-conditioning systems, the control over the use and production ofCFCs enjoying an annually increasing demand greatly affects ourresidential environment and the current social framework as a whole. Inconsequence, there is an urgent demand for development of novelrefrigerants with a high refrigerating performance, particularly a highcoefficient of performance, which can be substituted for R-11.Dichlorotrifluoroethane is a promising candidate substitute for R-11 tominimize ozone depletion, but has a low refrigerating performance incomparison with R-11.

We conducted extensive research to develop novel refrigerants which havea high coefficient of performance and which, if released into theatmosphere, would exert little influence on the ozone layer. Ourresearch revealed that when a certain class of CFC compound is mixedwith dichlorotrifluoroethane, a refrigerant can be obtained which canexhibit a higher coefficient of performance than trichlorofluoroethane.

The present invention provides a refrigerant comprising (1)dichlorotrifluoroethane and (2) at least one compound selected from thegroup consisting of chlorotetrafluoroethane, pentafluoroethane,tetrafluoroethane, 1-chloro-1,1-difluoroethane, 1,1,1-trifluoroethaneand 1,1-difluoroethane.

The present invention will be described blow in more detail withreference to, when required, the accompanying drawings.

FIGS. 1 to 6 show graphs indicative of the refrigerating capacity of therefrigerants according to the invention.

A preferred class of refrigerant composition according to the inventioncomprises (1) about 10 to about 97% by weight of dichlorotrifluoroethaneand (2) about 90 to about 3% by weight of at least one compound selectedfrom the group consisting of chlorotetrafluoroethane, pentafluoroethane(R-125), tetrafluoroethane, 1-chloro-1,1-difluoroethane (R-142b),1,1,1-trifluoroethane (R-143a) and 1,1-difluoroethane (R-152a). Therefrigerants containing the CFC compounds (1) and (2) in said range ofratio exhibit a higher coefficient of performance thandichlorofluoroethane singly used. Of refrigerants composed ofdichlorotrifluoroethane and chlorotetrafluoroethane or1-chloro-1,1-difluoroethane, a preferred one comprises about 40 to about90% by weight of the former and about 60 to about 10% by weight of thelatter. Of refrigerants composed of dichlorotrifluoroethane andpentafluoroethane, a preferred one comprises about 20 to about 97% byweight of the former and about 80 to about 3% by weight of the latter.Of refrigerants composed of dichlorotrifluoroethane andtetrafluoroethane, a preferred one comprises about 25 to about 97% byweight of the former and about 75 to about 3% by weight of the latter.Of refrigerants composed of dichlorotrifluoroethane and1,1,1-trifluoroethane, a preferred one comprises about 30 to about 97%by weight of the former and about 70 to about 3% by weight of thelatter. Of refrigerants composed of dichlorotrifluoroethane and1,1-difluoroethane, a preferred one comprises about 40 to about 97% byweight of the former and about 60 to about 3% by weight of the latter.The refrigerants having these preferred compositions can display ahigher coefficient of performance than R-11.

Examples of dichlorotrifluoroethane to be used in the invention are1,1-dichloro-2,2,2-trifluoroethane (R-123),1,2-dichloro-1,1,2-trifluoroethane (R-123a) and1,1-dichloro-1,2,2-trifluoroethane (R-123b). Examples ofchlorotetrafluoroethane for use herein are2-chloro-1,1,1,2-tetrafluoroethane (R-124) and1-chloro-1,1,2,2-tetrafluoroethane (R-124a). Examples oftetrafluoroethane for use herein are 1,1,1,2-tetrafluoroethane (R-134a)and 1,1,2,2-tetrafluoroethane (R-134). Among these examples, R-123 andR-123a or R-123b can achieve an equivalent effect in the composition ofthe invention and thus can be replaced by each other or mixed with eachother in use. Similar use can be made of R-124 and R-124a and alsoR-134a and R-134.

The refrigerants of the invention are smaller in the ratio of specificheat and lower in the temperature of gas discharged from the compressorthan chlorodifluoromethane (R-22) and are therefore suitable for use asa cooling medium for a refrigeration cycle using a relatively hightemperature as in an air-conditioning equipment of the heat pump type.

The composition of the invention can utilize the feature ofnon-azeotropic mixture. Generally a single compound or an azeotrope isvaporized at a constant temperature in an evaporator because of itsevaporation under constant pressure, whereas a non-azeotropic mixturehas a low temperature at the inlet of the evaporator and a hightemperature at the outlet thereof. On the other hand, a fluid to becooled is caused to flow in countercurrent to the refrigerant in theevaporator to undergo heat exchange and thus has a temperature gradientalong the flow direction even if the refrigerant is vaporized at aconstant temperature. In other words, a temperature difference betweenthe refrigerant and the fluid to be cooled diminishes in the evaporatoras the fluid flows forwardly. In use, the composition of the inventioncan be rendered close in temperature to the temperature gradient of thefluid to be cooled in the evaporator, so that the refrigerationefficiency, namely the coefficient of performance, can be enhanced.

The features of the invention will be clarified below with reference tothe following Examples and Comparison Example.

EXAMPLES 1 TO 6 AND COMPARISON EXAMPLE 1

Refrigerants were prepared by mixing together R-123 and R-124 in thevarious proportions shown below in Table 1 (weight ratio).

A refrigerator was operated with an output of 1 hp. using therefrigerants of the composition shown below in Table 1. Each refrigerantstarted condensation at 50° C. in a condenser and had a temperature of-50° C. in the inlet of the evaporator with a superheat degree of 5° C.Table 1 shows the maximum evaporating temperature (° C.), refrigeratingcapacity (kcal/m³), coefficient of performance and discharge temperature(° C.) at the compressor.

Table 1 also shows the results achieved by using R-123 alone (ComparisonExample 1).

FIG. 1 indicates graphs each illustrating the relationship between theproportions of R-123 and R-124 and the coefficient of performance (curveA) and the relationship between the proportions thereof and therefrigerating capacity (curve A'), respectively.

Table 1 and FIG. 1 reveal that the refrigerants of the present inventionhave outstanding properties.

                                      TABLE 1                                     __________________________________________________________________________           Composition of                                                                        Maximum              Discharge                                        refrigerant                                                                           evaporating                                                                          Refrigerating                                                                        Coefficient                                                                          temperature                                      (wt. %) temperature                                                                          capacity                                                                             of     at compressor                             Refrigerant                                                                          R-123                                                                             R-124                                                                             (°C.)                                                                         (kcal/m.sup.3)                                                                       performance                                                                          (°C.)                              __________________________________________________________________________    Comparison                                                                           100  0  -50.0  3.89   1.47   74.9                                      Example 1                                                                     Example 1                                                                            97   3  -48.9  4.36   1.51   73.7                                      Example 2                                                                            80  20  -45.1  6.81   1.65   69.2                                      Example 3                                                                            60  40  -43.5  9.41   1.68   65.9                                      Example 4                                                                            40  60  -43.8  11.7   1.60   63.6                                      Example 5                                                                            20  80  -45.7  14.0   1.43   61.2                                      Example 6                                                                            10  90  -47.5  15.5   1.32   59.2                                      __________________________________________________________________________

EXAMPLES 7 TO 12

The properties of refrigerants were investigated in the same manner asin Examples 1 to 6 with the exception of using the refrigerants preparedby mixing together R-123 and R-125 in the various proportions (weightratio) shown below in Table 2.

Table 2 shows the maximum evaporating temperature (° C.), refrigeratingcapacity (kcal/m³), coefficient of performance and discharge temperature(° C.) at the compressor in respect of the refrigerants.

FIG. 2 indicates graphs each illustrating the relationship between theproportions of R-123 and R-125 and the coefficient of performance (curveB) and the relationship between the proportions thereof and therefrigerating capacity (curve B'), respectively.

                                      TABLE 2                                     __________________________________________________________________________           Composition of                                                                        Maximum              Discharge                                        refrigerant                                                                           evaporating                                                                          Refrigerating                                                                        Coefficient                                                                          temperature                                      (wt. %) temperature                                                                          capacity                                                                             of     at compressor                             Refrigerant                                                                          R-123                                                                             R-125                                                                             (°C.)                                                                         (kcal/m.sup.3)                                                                       performance                                                                          (°C.)                              __________________________________________________________________________    Example 7                                                                            97   3  -41.7  7.69   1.84   70.0                                      Example 8                                                                            80  20  -25.2  29.5   2.88   64.4                                      Example 9                                                                            60  40  -20.3  51.2   3.06   65.0                                      Example 10                                                                           40  60  -22.8  61.2   2.61   68.9                                      Example 11                                                                           20  80  -31.5  58.1   1.79   76.7                                      Example 12                                                                           10  90  -38.9  53.1   1.28   82.0                                      __________________________________________________________________________

EXAMPLES 13 TO 18

The properties of refrigerants were investigated in the same manner asin Examples 1 to 6 with the exception of using the refrigerants preparedby mixing together R-123 and R-134a in the various proportions (weightratio) shown below in Table 3.

Table 3 shows the maximum evaporating temperature (° C.), refrigeratingcapacity (kcal/m³), coefficient of performance and discharge temperature(° C.) at the compressor in respect of the refrigerants.

FIG. 3 indicates graphs each illustrating the relationship between theproportions of R-123 and R-134a and the coefficient of performance(curve C) and the relationship between the proportions thereof and therefrigerating capacity (curve C'), respectively.

                                      TABLE 3                                     __________________________________________________________________________           Composition of                                                                        Maximum              Discharge                                        refrigerant                                                                           evaporating                                                                          Refrigerating                                                                        Coefficient                                                                          temperature                                      (wt. %) temperature                                                                          capacity                                                                             of     at compressor                             Refrigerant                                                                          R-123                                                                             R-134a                                                                            (°C.)                                                                         (kcal/m.sup.3)                                                                       performance                                                                          (°C.)                              __________________________________________________________________________    Example 13                                                                           97   3  -46.5  5.39   1.62   73.3                                      Example 14                                                                           80  20  -38.3  12.7   2.02   72.5                                      Example 15                                                                           60  40  -36.3  19.3   2.04   75.4                                      Example 16                                                                           40  60  -37.9  24.1   1.85   79.8                                      Example 17                                                                           20  80  -42.2  28.4   1.56   84.3                                      Example 18                                                                           10  90  -45.4  31.8   1.40   85.3                                      __________________________________________________________________________

EXAMPLES 19 TO 24

The properties of refrigerants were investigated in the same manner asin Examples 1 to 6 with the exception of using the refrigerants preparedby mixing together R-123 and R-142b in the various proportions (weightratio) shown below in Table 4.

Table 4 shows the maximum evaporating temperature (° C.), refrigeratingcapacity (kcal/m³), coefficient of performance and discharge temperature(° C.) at the compressor in respect of the refrigerants.

FIG. 4 indicates graphs each illustrating the relationship between theproportions of R-123 and R-142b and the coefficient of performance(curve D) and the relationship between the proportions thereof and therefrigerating capacity (curve D'), respectively.

                                      TABLE 4                                     __________________________________________________________________________           Composition of                                                                        Maximum              Discharge                                        refrigerant                                                                           evaporating                                                                          Refrigerating                                                                        Coefficient                                                                          temperature                                      (wt. %) temperature                                                                          capacity                                                                             of     at compressor                             Refrigerant                                                                          R-123                                                                             R-142b                                                                            (°C.)                                                                         (kcal/m.sup.3)                                                                       performance                                                                          (°C.)                              __________________________________________________________________________    Example 19                                                                           97   3  -48.7  4.49   1.52   74.7                                      Example 20                                                                           80  20  -44.7  7.47   1.67   75.6                                      Example 21                                                                           60  40  -43.6  10.4   1.68   77.9                                      Example 22                                                                           40  60  -44.2  13.1   1.61   80.3                                      Example 23                                                                           20  80  -46.3  16.0   1.50   81.6                                      Example 24                                                                           10  90  -47.8  17.8   1.45   81.3                                      __________________________________________________________________________

EXAMPLES 25 TO 30

The properties of refrigerants were investigated in the same manner asin Examples 1 to 6 with the exception of using the refrigerants preparedby mixing together R-123 and R-143a in the various proportions (weightratio) shown below in Table 5.

Table 5 shows the maximum evaporating temperature (° C.), refrigeratingcapacity (kcal/m³), coefficient of performance and discharge temperature(° C.) at the compressor in respect of the refrigerants.

FIG. 5 indicates graphs each illustrating the relationship between theproportions of R-123 and R-143a and the coefficient of performance(curve E) and the relationship between the proportions thereof and therefrigerating capacity (curve E'), respectively.

                                      TABLE 5                                     __________________________________________________________________________           Composition of                                                                        Maximum              Discharge                                        refrigerant                                                                           evaporating                                                                          Refrigerating                                                                        Coefficient                                                                          temperature                                      (wt. %) temperature                                                                          capacity                                                                             of     at compressor                             Refrigerant                                                                          R-123                                                                             R-143a                                                                            (°C.)                                                                         (kcal/m.sup.3)                                                                       performance                                                                          (°C.)                              __________________________________________________________________________    Example 25                                                                           97   3  -41.6  7.87   1.85   70.4                                      Example 26                                                                           80  20  -26.7  30.0   2.71   67.8                                      Example 27                                                                           60  40  -24.3  45.4   2.64   71.3                                      Example 28                                                                           40  60  -28.2  50.9   2.14   77.7                                      Example 29                                                                           20  80  -36.2  49.1   1.50   86.2                                      Example 30                                                                           10  90  -41.8  49.2   1.18   88.8                                      __________________________________________________________________________

EXAMPLES 31 TO 36

The properties of refrigerants were investigated in the same manner asin Examples 1 to 6 with the exception of using the refrigerants preparedby mixing together R-123 and R-152a in the various proportions (weightratio) shown below in Table 6.

Table 6 shows the maximum evaporating temperature (° C.), refrigeratingcapacity (kcal/m³), coefficient of performance and discharge temperature(° C.) at the compressor in respect of the refrigerants.

FIG. 6 indicates graphs each illustrating the relationship between theproportions of R-123 and R-152a and the coefficient of performance(curve F) and the relationship between the proportions thereof and therefrigerating capacity (curve F'), respectively.

                                      TABLE 6                                     __________________________________________________________________________           Composition of                                                                        Maximum              Discharge                                        refrigerant                                                                           evaporating                                                                          Refrigerating                                                                        Coefficient                                                                          temperature                                      (wt. %) temperature                                                                          capacity                                                                             of     at compressor                             Refrigerant                                                                          R-123                                                                             R-152a                                                                            (°C.)                                                                         (kcal/m.sup.3)                                                                       performance                                                                          (°C.)                              __________________________________________________________________________    Example 31                                                                           97   3  -44.7  6.30   1.70   73.6                                      Example 32                                                                           80  20  -36.3  16.2   2.07   78.7                                      Example 33                                                                           60  40  -36.3  23.0   1.96   87.6                                      Example 34                                                                           40  60  -39.2  27.7   1.74   96.0                                      Example 35                                                                           20  80  -43.6  33.1   1.53   101.7                                     Example 36                                                                           10  90  -46.5  37.4   1.45   102.2                                     __________________________________________________________________________

We claim:
 1. In the development of heating or cooling conditions in avapor-compression cycle using a liquid refrigerant, the improvementwherein the refrigerant comprises (1) about 10 to about 97% by weight ofdichlorotrifluoroethane and (2) about 90 to about 3% by weight of atleast one compound selected from the group consisting of1,1,1,2-tetrafluoroethane, 1,1,2,2-tetrafluoroethane,1-chloro-1,1-difluoroethane, 1,1,1-trifluoroethane and1,1-difluoroethane.
 2. A process according to claim 1 wherein therefrigerant comprises about 40 to about 90% by weight ofdichlorotrifluoroethane and about 60 to about 10% by weight of1-chloro-1,1-difluoroethane.
 3. A process according to claim 1 whereinthe refrigerant comprises about 25 to about 97% by weight ofdichlorotrifluoroethane and about 75 to about 3% by weight of at leastone of 1,1,1,2-tetrafluoroethane and 1,1,2,2-tetrafluoroethane.
 4. Aprocess according to claim 1 wherein the refrigerant comprises about 30to about 97% by weight of dichlorotrifluoroethane and about 70 to about3% by weight of 1,1,1-trifluoroethane.
 5. A process according to claim 1wherein the refrigerant comprises about 40 to about 97% by weight ofdichlorotrifluoroethane and about 60 to about 3% by weight of1,1-difluoroethane.